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J Rao

Publications and source records attributed to J Rao.

At least 55 records · Page 3Linked to original sources
PubMed1998

Affinity capillary electrophoresis: a physical-organic tool for studying interactions in biomolecular recognition.

Affinity capillary electrophoresis (ACE) is a technique that is used to measure the binding affinity of receptors to neutral and charged ligands. ACE experiments are based on differences in the values of electrophoretic mobility of free and bound receptor. Scatchard analysis of the fraction of bound receptor, at equilibrium, as a function of the concentration of free ligand yields the dissociation constant of the receptor-ligand complex. ACE experiments are most conveniently performed on fused silica capillaries using a negatively charged receptor (molecular mass < 50 kDa) and increasing concentrations of a low molecular weight, charged ligand in the running buffer. ACE experiments that involve high molecular weight receptors may require the use of running buffers containing zwitterionic additives to prevent the receptors from adsorbing appreciably to the wall of the capillary. This review emphasizes ACE experiments performed with two model systems: bovine carbonic anhydrase II (BCA II) with arylsulfonamide ligands and vancomycin (Van), a glycopeptide antibiotic, with D-Ala-D-Ala (DADA)-based peptidyl ligands. Dissociation constants determined from ACE experiments performed with charged receptors and ligands can often be rationalized using electrostatic arguments. The combination of differently charged derivatives of proteins - protein charge ladders - and ACE is a physical-organic tool that is used to investigate electrostatic effects. Variations of ACE experiments have been used to estimate the charge of Van and of proteins in solution, and to determine the effect of the association of Van to Ac2KDADA on the value of pKa of its N-terminal amino group.

Animals↗
PubMed1998

Study on Haemophilus influenzae type b diseases in China: the past, present and future.

Meningitis caused by Haemophilus influenzae type b (Hib) is a common and serious disease for which there now are WHO-certified vaccines that are recommended for universal infant immunization in North America and European countries. If these vaccines are to be recommended in Asia, it is necessary to know the incidence, age distribution and clinical outcome of Hib meningitis and other systemic infections in this region. Data on Hib disease in China are scanty. Hib meningitis was common during the 1950s in China, accounting for up to 16% of all of pyogenic meningitis (up to 38% of cases were caused by unknown pathogens), despite severe epidemics of meningococcal meningitis during that period. Since 1989 we have conducted hospital- and community-based etiologic and epidemiologic studies of bacterial meningitis. Hib accounts for 30 to 50% of bacterial meningitis in China. The incidence of Hib meningitis in Hefei City was 10.4 per 100000 children <5 years, a result relatively lower than in the West but higher than the rate of 2.7 found in a retrospective study in Hong Kong. Pneumonia is the primary cause of death for Chinese children. From 1991 to 1993 the average mortality of children<5 years because of pneumonia was 1563.2 per 100000. To achieve the goal of reducing the death rate of children by one-third by the year 2000, greater efforts should be made to reduce the mortality of children with pneumonia. Our preliminary study showed that about one-fourth to one-third of cases of pneumonia in Chinese children might be caused by Hib. Therefore Hib vaccination for infants and children in China might be an effective and valuable procedure to achieve the goal.

Child, Preschool↗
PubMed1998

SBA1 encodes a yeast hsp90 cochaperone that is homologous to vertebrate p23 proteins.

The Saccharomyces cerevisiae SBA1 gene was cloned by PCR amplification from yeast genomic DNA following its identification as encoding an ortholog of human p23, an Hsp90 cochaperone. The SBA1 gene product is constitutively expressed and nonessential, although a disruption mutant grew more slowly than the wild type at both 18 and 37 degreesC. A double deletion of SBA1 and STI1, encoding an Hsp90 cochaperone, displayed synthetic growth defects. Affinity isolation of histidine-tagged Sba1p (Sba1(His6)) after expression in yeast led to coisolation of Hsp90 and the cyclophilin homolog Cpr6. Using an in vitro assembly assay, purified Sba1(His6) bound to Hsp90 only in the presence of adenosine 5'-O-(3-thiotriphosphate) or adenyl-imidodiphosphate. Furthermore, interaction between purified Sba1(His6) and Hsp90 in yeast extracts was inhibited by the benzoquinoid ansamycins geldanamycin and macbecin. The in vitro assay was also used to identify residues in Hsp90 that are important for complex formation with Sba1(His6), and residues in both the N-terminal nucleotide binding domain and C-terminal half were characterized. In vivo analysis of known Hsp90 substrate proteins revealed that Sba1 loss of function had only a mild effect on the activity of the tyrosine kinase v-Src and steroid hormone receptors.

Amino Acid Sequence↗
PubMed1998

Postradiation morphea.

We describe a 54-year-old woman who developed right breast morphea after radiotherapy following a lumpectomy for infiltrating lobular carcinoma. Skin biopsy confirmed the histological features of morphea. Treatment was initiated with both topical and intralesional steroid, resulting in marked improvement. Morphea following radiotherapy is an infrequently recognized phenomenon. However, when diagnosed early it may be effectively managed with local steroid treatment.

Administration, Topical↗
PubMed1998

Bacterial infection and endotoxin in female reproductive tract in rats: correlation with the developmental status of preimplantation embryos.

During mammalian preimplantation development, a substantial numbers of embryos are believed to be lost for reasons that are unclear. Using female rats, we investigated whether the developmental status of embryos is influenced by bacterial infection and endotoxin in the reproductive tract. From the vagina of cycling rats (n = 11), 21 bacterial isolates were identified; they were Streptococcus faecalis (S. faecalis; 38%), Escherichia coli (E. coli; 19%), Acinetobactor calcoaceticus (A. calcoaceticus; 14%), and coagulase negative staphylococcus (14%), Micrococcus sp. (5%), Bacillus subtilis (B. subtilis; 5%) and Proteus vulgaris (P. vulgaris; 5%). From the vagina of day 4 pregnant rats (n = 12), 26 isolates were identified; they were S. faecalis (23%), A. calcoaceticus (23%), E. coli (15%), Micrococcus sp. (15%), B. subtilis (8%), P. vulgaris (4%), Staphylococcus aureus (4%), beta-hemolytic streptococcus (4%) and Pseudomonas aeruginosa (4%). Gram negative bacteria found in the vagina of cycling and day 4 pregnant rats were 38% and 46%, respectively. In both, bacterial load was 10(3)-10(5) colony forming units and there was no association with the abnormality of the recovered embryos. However, in two day 4 pregnant animals, pathogenic bacteria (Staphylococcus aureus and beta-hemolytic streptococcus) were isolated and embryos recovered from them were degenerated and deformed. The vagina of day 9 pregnant animals (n = 7) were, however, sterile. Consistently, in all animals, the upper reproductive tract (uterus and oviduct) was devoid of any bacteria and no anaerobic bacteria were isolated from any part of the tract. The levels of endotoxin in the vagina of cycling and day 4 pregnant rats were 1.35 +/- 0.1 and 1.17 +/- 0.1 endotoxin units (EU), respectively. It was undetectable in the oviduct and uterus of all animals (n = 5) except one which showed high levels of endotoxin in uterus (4.5 EU) and oviduct (2.2 EU) and the animal also produced degenerated and deformed embryos. These results indicate that common bacterial flora of vagina may not affect embryo development and the presence of pathogenic bacteria in the vagina and/or endotoxin in reproductive tract could be detrimental to viability of gametes and preimplantation embryos in rats.

Animals↗
PubMed1997

Uncoupling of cell cycle arrest from the expression of monocytic differentiation markers in HL60 cell variants.

Differentiation generally leads to cell cycle arrest. Human leukemia HL60 cells respond to the presence of 1,25-dihydroxyvitamin D3 (1,25D3) by expressing a number of markers of the monocyte/macrophage phenotype and become arrested predominantly in the G1 phase of the cell cycle. We have recently reported a series (A) of 1,25D3-resistant variants of HL60 cells which proliferate in the presence of 1,25D3 and do not express differentiation markers (Exp. Cell Res. 224, 312, 1996). We now describe another series (B) of such variants, which differ from A series cells grown in similar concentrations of 1,25D3 in that they express the CD14 antigen and nonspecific esterase, characteristic of the monocyte, while continuing to proliferate and they develop hypotetraploid DNA (4C) content at higher concentrations of ambient 1,25D3 than the A series cells. Cells in the B series with 4C DNA content (100B and 200B) also differed from the A series 4C cells by the absence of DNA binding by the full-length Sp1 transcription factor. However, B series cells resembled the A series cells in exhibiting faster growth rates than the parental HL60 cells and showed high levels of vitamin D receptor and retinoid receptor X proteins. These results show that the initial steps in the 1,25D3 signaling pathway are intact in B series resistant cells and lead to the appearance of early markers of monocytic differentiation. However, the progression to subsequent events which comprise terminal differentiation and cell cycle arrest is halted during the adaptation to the presence of 1,25D3 in these cells. Thus, the availability of these variant cells should provide a system for studying the link between differentiation and cell cycle arrest.

Antigens, Differentiation, Myelomonocytic↗
PubMed1997

Whole-blood test for total cholesterol by a self-metering, self-timing disposable device with built-in quality control.

A whole-blood test for total cholesterol has been developed that is performed in a low-cost disposable flow device without user intervention (after sample addition). The device meters the sample, separates plasma from erythrocytes, and precisely times plasma flow into various reagent compartments, including a quality-assurance chamber. Test results are displayed as a well-defined and easily readable color bar. A quality-control window attests to the integrity of the test components. Here, we describe the assembly and individual functions of the device and report its performance characteristics. Precision and accuracy studies in four clinical studies at independent locations yielded total imprecision of <5% and an average bias of 1.35% vs the Abell-Kendall method.

Cholesterol↗
PubMed1996

Transition to tetraploidy in 1,25-dihydroxyvitamin D3-resistant HL60 cells is preceded by reduced growth factor dependence and constitutive up-regulation of Sp1 and AP-1 transcription factors.

Increased ploidy is an ominous event in the progression of human malignancies. It is usually associated with an increased growth rate of the neoplastic cells and a generally more autonomous and aggressive biological behavior. However, it has not been established whether the more rapid growth rate and growth factor independence are consequences of the polyploid, karyotypically increasingly aberrant nature of these cells or whether the accelerated, more autonomous growth contributes to polyploidization. In this study, we have examined a recently described (H. J. Wajchman et al., Exp. Cell Res., 224: 312-322, 1996) series of sublines of HL60 cells with increasing resistance to the monocytic differentiation-inducing steroid hormone 1,25-dihydroxyvitamin D3 (1,25D3) and found that growth factor independence, shown by reduced requirement for serum supplementation of the medium and the ability to grow at low seeding densities, precedes polyploidization of these cultures. The growth factor independence was found to be accompanied by constitutive changes in the DNA binding pattern of the ubiquitous transcription factor Sp1, characteristic of an exposure to 1,25D3. Similar changes in the pattern of AP-1 binding were also observed in the 1,25D3-resistant HL60 sublines, but the intensity of the DNA binding by AP-1 was increased only in sublines with resistance to 1,25D3 but still near-diploid. The data suggest that the culture of HL60 cells in the presence of 1,25D3 results in constitutive up-regulation of growth-related machinery that reduces the need for growth factors and cytokines and demonstrate that this increased growth potential precedes polyploidization of the culture populations.

Animals↗
PubMed1996

Effects of pancreatic spasmolytic Polypeptide (PSP) on epithelial cell function.

Trefoil peptides are expressed near endodermal ulcerations and may modulate epithelial repair. The trefoil pancreatic spasmolytic polypeptide (PSP) was tested for growth activity in vitro on epithelial cells and in vivo following intragastric or intravenous infusion in parenterally fed intact rats. Ion transport was assessed as changes in short-circuit current in rat intestine and adenocarcinoma cells in Ussing chambers. PSP stimulated growth of MCF-7 and Colo-357 cells, but only in the presence of extracellular glutathione (GSH). The effect was attenuated by GSH depletion with buthionine sulphoximine, even in GSH-containing media. When GSH-reduced PSP was carboxymethylated with iodoacetic acid, it still depended on extracellular GSH for its growth effect. Intestinal epithelial proliferation in rats was not affected by either intravenous or intraluminal infusion. PSP had no effect on basal or stimulated ion flux in rat jejunum or epithelial monolayers. The peptide did not compete with 125I-labeled epidermal growth factor for its receptor. [14C]Iodoacetamide treatment of PSP, followed by prolonged tryptic digestion yielded predominantly a 14C-labeled tetrapeptide fragment containing Cys1O4, with a lesser quantity of a 14C-labeled 15-amino-acid peptide containing Cys95 (molar ratio 15:1). GSH may predominantly reduce the Cys6-Cys1O4 terminal disulphide bond in PSP. We conclude that some epithelia may exhibit a growth response to PSP if extracellular GSH is present. Reduction of PSP by GSH is not necessary for this response, suggesting that the trefoil receptor or its signal transduction is GSH sensitive. PSP could assist wound healing by interactions with epithelial cells exposed concurrently to a local high GSH concentration.

Animals↗
PubMed1996

Interferon augments the cytotoxicity of hydroxyurea without enhancing its activity against the M2 subunit of ribonucleotide reductase: effects in wild-type and resistant human colon cancer cells.

The effects of prolonged exposure to the ribonucleotide reductase (RR) inhibitor, hydroxyurea (HU), were assessed in the presence or absence of recombinant interferon alfa-2a (IFN) in wild-type human colon cancer cells (HT-29) and variants expressing low-level resistance to HU (R200). IFN at nontoxic concentrations decreased the IC50 of HU from 368 microM to 215 microM (P < 0.01) in wild-type cells, but not in the resistant variants. Potential cellular targets for the HU/IFN interaction were examined. In wild-type, but not resistant cells, treatment with HU at clinically achievable concentrations (1000 microM) resulted in rapid early inhibition of RR activity between 4 and 24 h after treatment with a maximal decrease of 65% at 12 h, decreases in cellular levels of dATP, dCTP and dGTP by 50-90% over the same time course, and a two- to fourfold increase in the level of mRNA for both the M1 and M2 subunits of RR, at 24, but not between 1 and 4 h, which probably represents a response to the earlier decrease in RR activity. IFN at a clinically achievable concentration (500 U/ml) failed to augment the effects of HU on RR protein, RR mRNA levels or RR enzyme activity in either the wild-type or resistant cells, suggesting that the mechanism by which IFN augments the effects of HU in the wild-type cells is independent of the effects of HU on M2.

Base Sequence↗
PubMed1996

Lipid peroxidation and activities of antioxidant enzymes in iron deficiency and effect of carcinogen feeding.

Iron deficiency has been implicated in increasing the risk of GI tract cancers in humans. Among various mechanisms of carcinogenesis, oxidative damage to DNA is well known and, hence, the present experimental study was undertaken to investigate lipid peroxidation and activities of different antioxidant enzymes in iron deficiency to explain the higher risk of tumorigenesis. Two groups of male weanling Fischer rats maintained on iron sufficient (C) or iron deficient (D) diets for a period of 32 weeks were subdivided, from 3 weeks onwards, into two subgroups each. The carcinogen, dimethyl hydrazine was fed at a dose of 30 mg/kg/week IG for a period of 9 weeks to groups that were designated as (C+) and (D+). The other two subgroups (C-) and (D-) served as controls. After the experimental period, hepatic assays for lipid peroxidation (MDA production) and activities of various antioxidant enzymes were carried out. The results showed that MDA production was elevated by 50% and activity of superoxide dismutase significantly depressed in carcinogen-fed, iron-deficient group (D+) by 28% compared to deficient (D-) group. There was an increase in hepatic selenium-dependent glutathione peroxidase activity in iron-deficient and iron-deficient, carcinogen-treated groups to the extent of 57 and 59%, respectively, as compared to controls; however, induction of enzyme in response to carcinogen feeding, observed in the control group, was not evident in iron deficiency. Liver catalase was not altered between control and deficient groups. These results suggest that prolonged iron deficiency superimposed with carcinogen ingestion may render the host susceptible to a greater risk of tumorigenesis through oxidative stress.

1,2-Dimethylhydrazine↗
PubMed1996

Hypersomnia associated with a focal pontine lesion.

A 50-year-old woman developed intractable excessive sleepiness after undergoing the surgical removal of a brainstem cholesteatoma. The 24-hour ambulatory monitoring revealed a normal architecture of sleep contents, with 62.7% of the time spent in sleep. Auditory and somatosensory evoked responses showed abnormal patterns. The MRI scan of her brain showed an extensive nonprogressive lesion in the brainstem. We speculate that the problem underlying the patient's hypersomnia is a defect in the ascending reticular activating system (ARAS) rather than in the REM and NREM sleep mechanisms.

Cholesteatoma↗
PubMed1996

Active immunization of rats with chicken egg thiamin carrier protein results in early embryonic loss at periimplantation stages.

Active immunization with chicken egg white thiamin carrier protein (TCP) was performed to assess the functional importance of the vitamin carrier during gestation in rats. Towards this, fertile female rats were immunized with heterologous TCP and when the circulatory titres of anti-TCP IgG were high, these animals were mated with fertile male rats. Progression of pregnancy was monitored by measuring circulatory progesterone levels. A sudden fall in the steroid hormonal levels around day 8 post coitus was observed. Histological examination of the uterine tissue sections on day 7 revealed that active immunization with TCP affected the blastocyst viability resulting in unsuccessful implantation and hence pregnancy termination.

Animals↗
PubMed1996

G-actin as a risk factor and modulatable endpoint for cancer chemoprevention trials.

Because tumorigenesis is an ongoing process, biomarkers can be used to identify individuals at risk for bladder cancer, and treatment of those at risk to prevent or slow further progression could be an effective means of cancer control given accurate individual risk assessment. Tumorigenesis proceeds through a series of defined phenotypic changes, including those in genetically altered cells destined to become cancer as well as in surrounding normal cells responding to the altered cytokine environment. A panel of biomarkers for the changes can provide a useful system for individual risk assessment in cancer patients and in individuals exposed to carcinogens. The use of such markers can increase the specificity of chemoprevention trials by targeting therapy to patients likely to respond, and thereby markedly reduce the costs of the trials. Previous studies in our laboratories showed the cytoskeletal proteins G- and F-actin reflect differentiation-related changes in cells undergoing tumorigenesis and in adjacent "field" cells, and a pattern of low F-actin and high G-actin is indicative of increased risk. Actin changes may be a common feature in genetic and epigenetic carcinogenic mechanisms. In a group of over 1600 workers exposed to benzidine, G-actin correlated with exposure, establishing it as an early marker of effect. In another study, a profile of biomarkers was monitored in patients who underwent transurethral resection of bladder tumor (TURBT) and received Bacillus Calmette Guerin (BCG) and/or DMSO. The primary objective was to determine how the defined biomarkers expressed in the tumor and the field correlate with clinical response and recurrence. DMSO, known to modulate G-actin in vitro, was used as an agent. Results strongly support the hypothesis that cytosolic G-actin levels measured by quantitative fluorescence image analysis (QFIA) can be an important intermediate endpoint marker for chemoprevention and that the p300 (M344) and DNA ploidy markers identify a high-risk group that requires more aggressive therapy and recurrence monitoring. Further research with other markers has shown that DD23 and nuclear actin, both of which identify late, specific changes, may increase the battery of useful markers. Taken together these studies show how biomarkers are employed to study individuals at risk, aid in the selection of chemopreventive compounds and assist in the understanding of the pathogenesis of malignancy.

Actins↗
PubMed1996

Acute bacterial meningitis in children in Hefei, China 1990-1992.

OBJECTIVE: To obtain etiologic and epidemiologic information about bacterial meningitis, especially the H influenza type B (Hib), from a medium-sized city, Hefei, China. METHODS: Data were collected prospectively over 3 years, from 1990 to 1992 by a well-organized group including 13 hospitals. All children with a clinical diagnosis of acute bacterial meningitis were enrolled and the specimens were taken for the etiologic studies. CSF and blood were tested by standard bacteriologic technique. CSF, blood and concentrated urine were tested directly for detection of antigen by countercurrent immuno-electrophoresis (CIE). Data were analyzed by epidemiologic methods. RESULTS: Bacterial culture and CSF Gram's staining were positive only in 13.3% and 11.7%, respectively. Bacterial antigen detection was positive in up to 90% by CIE which was more sensitive than bacterial culture (chi 2 = 67.7, P < 0.005). The annual incidence of acute bacterial meningitis in the city is calculated as 9.3 cases/100,000 children from 1 month to 15 years of age and 19.2 cases/100,000 children from 1 month to 5 years of age. Hib meningitis accounted for 51.7%, N. meningitis (Nm) for 38.3%, and S. pneumoniae (Sp) for 8.3%. There was no significant seasonal variation. Of the patients, 76.7% were children under 5 years of age, and 51.7% under 1 year of age. The case fatality rate was 11.7% for all bacterial meningitis, 9.7% for Hib, 17.4% for Nm and 20% for Sp. A total of 22.6% of survivors suffered from neurological or psychological problems. CONCLUSIONS: Using antigen detection combined with bacterial culture, we could make an etiologic diagnosis in up to 90% of the patients in this group. Hib, Nm and Sp were the predominant pathogens, which was similar to the findings in other countries. Hib was the most common cause of bacterial meningitis, but the incidence was much lower than in most parts of the world.

Child↗
PubMed1995

3-deaza- and 7-deaza-5'-noraristeromycin and their antiviral properties.

An enantiospecific synthesis of 3-deaza-5'-noraristeromycin as its dihydrochloride ((-)-6) has been accomplished in six steps beginning with the reaction of (+)-(1R,4S)-4-hydroxy-2-cyclopenten-1-yl acetate with 4-chloro-1H-imidazo[4,5-c]pyridine. The preparation of 7-deaza-5'-noraristeromycin ((-)-7) was described previously. Compounds (-)-6 and (-)-7 were evaluated for antiviral activity against a large number of viruses. Compound (-)-6 produced an antiviral activity pattern similar to 5'-noraristeromycin but was less potent. Compound (-)-6 inhibited CEM cell proliferation at a 50% inhibitory concentration of 27 micrograms/mL but proved not inhibitory to HEL cell proliferation and not toxic to E6SM, HeLa, Vero, and MDCK cells at concentrations up to 200 micrograms/mL. While (-)-6 showed inhibition of S-adenosyl-L-homocysteine (AdoHcy) hydrolase, it was less inhibitory than 5'-noraristeromycin. Compound (-)-7 displayed no antiviral properties or inhibitory effects toward AdoHcy hydrolase.

Adenosine↗